[libvirt] [PATCH 1/3] polkit: Adjust message when action-id isn't found

[John Ferlan]

When there isn't a ssh -X type session running and a user has not
been added to the libvirt group, attempts to run 'virsh -c qemu:///system'
commands from an otherwise unprivileged user will fail with rather
generic or opaque error message:

    "error: authentication failed: no agent is available to authenticate"

This patch will adjust the error message to help reflect not only
that it was a polkit agent, but which 'action-id' was not found. It
does so carefully, by adding to the text rather than adjusting it
since virpolkittest is looking for a specific string. The result on
a failure then becomes:

    "error: authentication failed: no agent is available to authenticate -
     polkit agent 'org.libvirt.unix.manage' is not available"

A bit more history on this - at one time a failure generated the
following type message when running the 'pkcheck' as a subprocess:

"error: authentication failed: polkit\56retains_authorization_after_challenge=1
Authorization requires authentication but no agent is available."

but, a patch was generated to adjust the error message to help provide
more details about what failed. This was pushed as commit id '96a108c99'.
That patch prepended a "polkit: " to the output. It really didn't solve
the problem, but gave a hint.

After some time it was deemed using DBus API calls directly was a
better way to go (since pkcheck calls them anyway). So, commit id
'1b854c76' (more or less) copied the code from remoteDispatchAuthPolkit
and adjusted it. Then commit id 'c7542573' adjusted the remote.c
code to call the new API (virPolkitCheckAuth). Finally, commit id
'308c0c5a' altered the code to call DBus APIs directly. In doing
so, it reverted the failing error message to the generic message
that would have been received from DBus anyway.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/util/virpolkit.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/util/virpolkit.c b/src/util/virpolkit.c
index 8da91f2..56b1c31 100644
--- a/src/util/virpolkit.c
+++ b/src/util/virpolkit.c
@@ -1,7 +1,7 @@
 /*
  * virpolkit.c: helpers for using polkit APIs
  *
- * Copyright (C) 2013, 2014 Red Hat, Inc.
+ * Copyright (C) 2013, 2014, 2016 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -121,8 +121,10 @@ int virPolkitCheckAuth(const char *actionid,
             virReportError(VIR_ERR_AUTH_CANCELLED, "%s",
                            _("user cancelled authentication process"));
         else if (is_challenge)
-            virReportError(VIR_ERR_AUTH_FAILED, "%s",
-                           _("no agent is available to authenticate"));
+            virReportError(VIR_ERR_AUTH_FAILED,
+                           _("no agent is available to authenticate - "
+                             "polkit agent '%s' is not available"),
+                           actionid);
         else
             virReportError(VIR_ERR_AUTH_FAILED, "%s",
                            _("access denied by policy"));
-- 
2.5.0